Misc 1 - Chapter 2 Class 12 Inverse Trigonometric Functions
Last updated at Dec. 16, 2024 by Teachoo
Finding principal value
Principal Value
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Chapter 2 Class 12 Inverse Trigonometric Functions
Concept wise
Transcript
Misc 1 Find the value of cos-1 (cos〖13π/6〗 ) Let y = cos-1 (cos〖13π/6〗 ) cos y = cos 13π/6 cos y = cos (390°) But, Range of cos−1 is [0, π] i.e. [0°, 180°] Hence, y = 390° not possible Now, cos y = cos (390°) cos y = cos (360° + 30°) cos y = cos (30°) cos y = cos (𝜋/6) ∴ y = 𝝅/𝟔 Which is in the range of cos-1 i.e. [0, π] Hence , cos −1 (cos 13π/6 " " ) = 𝝅/𝟔
